Work vehicles

Abstract

To provide a work vehicle capable of performing switch drive of a stepped variable transmission device smoothly.SOLUTION: A rice transplanter 1 includes a stepped variable transmission device 40, a speed change lever 18, which is a stepped speed change operation part, and a control device 4 that functions as a speed change control part 70. The stepped variable transmission device 40 is switched to any one shift position, and shifts the power to be transmitted from an engine 11 to a pair of front wheels 13 and a pair of rear wheels 14. The speed change lever 18 receives a switching operation of the stepped variable transmission device 40, and the speed change control part 70 controls the switch drive of the stepped variable transmission device 40 on the basis of a result of the detection of the switching operation. The stepped variable transmission device 40 includes a main speed change member 45 switched to any one shift position and a main speed change shaft 41 for axially supporting the main speed change member 45. The speed change control part 70 executes control to rotate the main speed change shaft 41 in a predetermined rotation direction when it is determined that the stepped variable transmission device 40 has not completed the switch drive to a shift position corresponding to the switching operation by the speed change lever 18.SELECTED DRAWING: Figure 9

Description

Technical Field

[0001] The present invention relates to a work vehicle equipped with a stepped transmission having a plurality of shift positions.

Background Art

[0002] Conventionally, work vehicles such as rice transplanters are equipped with a continuously variable transmission that continuously changes the power transmitted from the power source to the traveling unit, or a stepped transmission that has a plurality of shift positions and changes gears stepwise. The stepped transmission has, for example, a plurality of shift positions such as a forward position, a neutral position, and a reverse position for switching between forward and reverse, or a low speed position, a medium speed position, a high speed position, etc. for switching speed ranges. The work vehicle includes an actuator (shift drive member) that performs a switching drive to switch the shift member of the stepped transmission to any shift position, and a shift lever (stepped shift operation unit) that receives the switching operation of the stepped transmission. The work vehicle detects the operation position of the shift lever and drives the actuator according to the detection result to perform the switching drive of the stepped transmission.

[0003] For example, the work vehicle disclosed in Patent Document 1 includes a transmission that changes the output from the drive source to the traveling unit by changing the position of the shift member, an actuator that changes the position of the shift member, a cross lever type operating tool that can be operated in the front-rear, left-right directions and is biased to return to the neutral operation position, and a control device configured to operate the actuator according to the front-rear direction operation of the operating tool to switch the gear stage of the transmission, and to make the functions different according to the left-right direction operation of the operating tool according to the gear stage of the transmission.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In work vehicles, actuators are used to drive the gear shifting components of a stepped transmission. However, the gear shifting drive may not be completed smoothly due to phase misalignment of the clutch, which is a gear shifting component, or torque stagnation caused by gear engagement. For example, in work vehicles, the gear shifting drive of the gear shifting components of a stepped transmission is usually performed when the vehicle is stopped. However, if the gear shift shaft supporting the gear shifting components, such as slide gear type or collar shift type, is completely stopped or transmitting power, the gear shifting drive may not be performed smoothly.

[0006] The present invention aims to provide a work vehicle that can smoothly perform the switching drive of a stepped transmission. [Means for solving the problem]

[0007] To solve the above problems, the work vehicle of the present invention comprises a stepped transmission that changes the speed of power transmitted from a power source to a running section by switching to one of a plurality of gear positions, a stepped transmission operation unit that receives a switching operation of the stepped transmission, and a control unit that controls the switching drive of the stepped transmission based on the detection result of the switching operation by the stepped transmission operation unit, wherein the stepped transmission has a gear shift member that can be switched to one of the plurality of gear positions and a gear shift shaft that pivotally supports the gear shift member, and the control unit controls the gear shift shaft to rotate in a predetermined rotational direction when it is determined that the stepped transmission has not completed the switching drive to the gear position corresponding to the switching operation by the stepped transmission operation unit. [Effects of the Invention]

[0008] The present invention provides a work vehicle that can smoothly perform the switching drive of a stepped transmission. [Brief explanation of the drawing]

[0009] [Figure 1] This is a left side view showing a rice transplanter according to an embodiment of the present invention. [Figure 2]This is a perspective view from above showing various operating parts and the transmission of a rice transplanter according to an embodiment of the present invention. [Figure 3] This is a top view showing the gear shift lever of a rice transplanter according to an embodiment of the present invention. [Figure 4] This is a perspective view from above of the transmission of a rice transplanter according to an embodiment of the present invention. [Figure 5] This is a perspective view from below showing the transmission of a rice transplanter according to an embodiment of the present invention. [Figure 6] This is a top view showing the transmission of a rice transplanter according to an embodiment of the present invention. [Figure 7] This is a transmission mechanism diagram showing the transmission of a rice transplanter according to an embodiment of the present invention. [Figure 8] This is a cross-sectional view showing the main speed shifting member in the transmission of a rice transplanter according to an embodiment of the present invention, viewed from the side. [Figure 9] Block diagram showing a rice transplanter according to an embodiment of the present invention. [Figure 10] This flowchart shows an example of the operation of a rice transplanter according to an embodiment of the present invention. [Modes for carrying out the invention]

[0010] A rice transplanter 1, which is an embodiment of the work vehicle of the present invention, will be described with reference to the drawings. As shown in Figure 1, the rice transplanter 1 comprises a vehicle body 2 and a planting unit 3, and is configured to perform seedling planting work by the planting unit 3 while the vehicle body 2 moves. Furthermore, as shown in Figure 9, the rice transplanter 1 is equipped with a control device 4 for controlling the vehicle body 2 and the planting unit 3.

[0011] The vehicle body 2 comprises a body frame 10 and an engine 11 (power source) and a transmission 12 (speed changer) attached to the front of the body frame 10 near the center in the left-right direction. The vehicle body 2 also comprises a pair of front wheels 13 rotatably attached to the front of the body frame 10 at both ends in the left-right direction, and a pair of rear wheels 14 rotatably attached to the rear of the body frame 10 at both ends in the left-right direction, as the running section.

[0012] The vehicle body 2 is equipped with a driver's seat 15 near the center of the machine frame 10, and around the driver's seat 15 are driving controls such as a steering wheel 16, a gear shift pedal 17, and a gear shift lever 18, as shown in Figures 1 and 2. The vehicle body 2 is equipped with multiple spare seedling trays 19 on the machine frame 10.

[0013] The engine 11 generates rotational power to drive each part and is covered from above by the bonnet 20. The transmission 12 is connected to the engine 11 and transmits the power from the engine 11 to the running gear consisting of a pair of front wheels 13 and a pair of rear wheels 14, after changing the gear ratio. As shown in Figures 4 to 7, the transmission 12 includes a continuously variable transmission 30 that changes the gear ratio of the power from the engine 11 in a stepless manner, and a stepped transmission 40 that changes the gear ratio in steps with multiple gear positions. The transmission 12 is also connected to a power take-off shaft (PTO shaft) 21 located at the rear of the vehicle body 2 and transmits the power from the engine 11 to the planting unit 3 via the PTO shaft 21. Details of the transmission 12 will be described later.

[0014] The pair of front wheels 13 and the pair of rear wheels 14 rotate in response to power transmitted from the engine 11 and transmission 12, causing the vehicle body 2 to move forward or backward. The pair of front wheels 13 also steer in response to the operation of the steering wheel 16, steering the vehicle body 2.

[0015] The steering wheel 16 is arranged in front of the driver's seat 15 and behind the bonnet 20, and the steering transmitted to the pair of front wheels 13 is adjusted according to the rotational operation of the steering wheel 16 by the operator. The shift pedal 17 is a continuously variable transmission operation unit that receives the adjustment operation of the continuously variable transmission device 30 of the transmission 12, and is arranged at the lower front part of the driver's seat 15. A continuously variable operation detection unit 17a (see FIG. 9) for detecting adjustment operations such as depression by the operator is provided for the shift pedal 17, and the control device 4 controls the continuously variable transmission device 30 based on the detection result of the continuously variable operation detection unit 17a, so that the power transmitted to the traveling unit composed of the pair of front wheels 13 and the pair of rear wheels 14 is adjusted continuously. The continuously variable operation detection unit 17a is configured to be able to detect the opening degree of the shift pedal 17. Note that when the shift pedal 17 is not depressed, the opening degree is 0%, and when the depression is maximum (MAX), the opening degree is fully open (100%).

[0016] The shift lever 18 is a stepped transmission operation unit that receives the switching operation of the stepped transmission device 40 of the transmission 12, and is arranged on the left side of the steering wheel 16. A stepped operation detection unit 18a (see FIGS. 2 and 9) for detecting the shift operation by the operator is provided for the shift lever 18, and the control device 4 controls the stepped transmission device 40 based on the detection result of the stepped operation detection unit 18a, so that the stepped transmission device 40 is switched to any one of a plurality of shift positions. The stepped operation detection unit 18a is composed of, for example, a lever position sensor provided at the fulcrum of the shift lever 18. The shift lever 18 receives a main shift operation for switching the forward travel, reverse travel, and stop of the rice transplanter 1, and a sub-shift operation for switching the planting travel and the moving travel as the switching operation of the stepped transmission device 40. Note that when the shift lever 18 is switched to the moving travel, the traveling direction of the rice transplanter 1 is the same as the planting travel direction by the transmission 12, but by changing the gear ratio, a driving force faster than the planting travel can be transmitted to the traveling unit.

[0017] The shift lever 18 has a plurality of operating positions. For example, as shown in FIG. 3, as the operating positions for main shift operations, it has a forward operation 18b, a neutral operation 18c, and a reverse operation 18d, and as the operating positions for sub-shift operations, it has a planting operation 18e and a movement operation 18f. Note that the forward operation 18b corresponding to forward travel and the planting operation 18e corresponding to planting travel may be at the same operating position. Further, the shift lever 18 may have a seedling connection operation 18g as an operating position for sub-shift operations.

[0018] The planting unit 3 is disposed behind the vehicle body unit 2 and is connected to the vehicle body unit 2 via a lift link mechanism 22. The lift link mechanism 22 enables the planting unit 3 to be lifted and lowered with respect to the vehicle body unit 2. The planting unit 3 includes a planting input case portion 23, a plurality (for example, three) of planting units 24, a seedling mounting table 25, and a plurality of floats 26. The planting unit 3 is configured to sequentially supply seedlings from the seedling mounting table 25 to each planting unit 24 and perform planting operations for a plurality of rows by the plurality of planting units 24. The planting input case portion 23 is configured to transmit the power transmitted from the transmission 12 via the PTO shaft 21 to the plurality of planting units 24.

[0019] The plurality of planting units 24 are arranged at intervals in the left-right direction. Each planting unit 24 includes a planting transmission case portion 27 and a rotating case portion 28. The front portion of the planting transmission case portion 27 is connected to the planting input case portion 23, and power is transmitted via the planting input case portion 23. The rotating case portion 28 is provided on both the left and right sides of the planting transmission case portion 27 and is rotatably attached to the rear portion of the planting transmission case portion 27. Two planting claws 29 are attached to the outer side in the left-right direction (the side opposite to the planting transmission case portion 27 side) of each rotating case portion 28.

[0020] The two planting claws 29 are rotatably mounted on the rotating case section 28 at both ends of the rotating case section 28, spaced apart from the axis of rotation of the rotating case section 28 relative to the planting transmission case section 27. As the rotating case section 28 rotates relative to the planting transmission case section 27, the two planting claws 29 rotate around the axis of rotation of the rotating case section 28. At this time, each planting claw 29 rotates while passing through a scraping position for scraping seedlings from the seedling mat on the seedling tray 25 and a planting position for planting seedlings in the field.

[0021] The seedling tray 25 is positioned in front of and above the multiple planting units 24 and is configured to hold seedling mats. The float 26 is pivotably mounted below the planting section 3, and the lower surface of the float 26 contacts the field surface, stabilizing the planting position of the planting section 3 relative to the field surface.

[0022] Next, the transmission 12 will be explained with reference to Figures 2, 4 to 8.

[0023] In the transmission 12, the continuously variable transmission 30 transmits power from the engine 11 to the stepped transmission 40 by continuously changing the speed. For example, as shown in Figures 4 to 7, the continuously variable transmission 30 is configured as a hydraulic mechanical transmission (HMT) by comprising a hydraulic continuously variable transmission 31 (HST) and a planetary gear mechanism 32. The hydraulic continuously variable transmission 31 is connected to the planetary gear mechanism 32 and transmits power from the engine 11 to the planetary gear mechanism 32 by continuously changing the speed. The planetary gear mechanism 32 is composed of planetary gears, etc., and is connected to the main transmission shaft 41 (transmission shaft) provided in the stepped transmission 40, and transmits power from the hydraulic continuously variable transmission 31 to the main transmission shaft 41, causing the main transmission shaft 41 to rotate.

[0024] As shown in Figures 2 and 9, the continuously variable transmission 30 includes a continuously variable transmission drive member 33, such as an actuator, which performs the regulating drive of the hydraulic continuously variable transmission 31, and a continuously variable transmission operating unit 34, such as a drive motor, which operates the continuously variable transmission drive member 33. The continuously variable transmission operating unit 34 is controlled and operated by the control device 4 to operate the continuously variable transmission drive member 33, thereby regulating the drive of the hydraulic continuously variable transmission 31 and changing the power.

[0025] In the transmission 12, the stepped transmission 40 includes a main transmission shaft 41 (transmission shaft), a sub-transmission shaft 42, a reverse transmission shaft 43, and a brake 44, as shown in Figures 4 to 7. The main transmission shaft 41 is provided with a main transmission member 45 and a first PTO gear 46, and the sub-transmission shaft 42 is provided with a sub-transmission member 47, a first transmission gear 48, a second transmission gear 49, and a second PTO gear 50. The reverse transmission shaft 43 is provided with a reverse gear 51.

[0026] The main transmission member 45 has multiple transmission positions: a forward position, a neutral position, and a reverse position. It switches to any of these transmission positions to change the speed of the power transmitted from the main transmission shaft 41. The main transmission member 45 may be composed of any transmission means, such as a ball clutch, a slide gear, or a collar shift, but in this embodiment, as shown in Figure 8, an example in which it is composed of a ball clutch is shown.

[0027] When the main transmission member 45 is switched to the forward position, the main transmission shaft 41 is connected to the main transmission shaft forward gear 68, and power is transmitted from the main transmission shaft forward gear 68 to the auxiliary transmission shaft 42 via the auxiliary transmission member 47. When the main transmission member 45 is switched to the reverse position, the main transmission shaft 41 is connected to the main transmission shaft reverse gear 69, and power is transmitted from the main transmission shaft reverse gear 69 to the reverse transmission shaft 43 via the reverse gear 51. The reverse gear 51 is also connected (measuring) to the first transmission gear 48 of the auxiliary transmission shaft 42, and power is transmitted to the auxiliary transmission shaft 42 via the first transmission gear 48. When the main transmission member 45 is switched to the neutral position, the main transmission shaft 41 is not connected to either the main transmission shaft forward gear 68 or the main transmission shaft reverse gear 69, and power is not transmitted.

[0028] As shown in Figures 2 and 9, a main transmission drive member 52, such as an actuator that performs switching drive, is attached to the main transmission member 45, and a stepped transmission actuation unit 66, such as a drive motor that operates the main transmission drive member 52, is connected to the main transmission drive member 52. The stepped transmission actuation unit 66 is controlled and operated by the control device 4 to operate the main transmission drive member 52 and perform switching drive of the main transmission member 45. For example, the main transmission member 45, which consists of a ball clutch, is configured as shown in Figure 8, with two balls 45a corresponding to the main transmission shaft forward gear 68 and the main transmission shaft reverse gear 69, respectively, a shifter 45b that shifts in accordance with the drive of the main transmission drive member 52, and a ball engaging member 45c.

[0029] The ball engaging member 45c is an annular member provided on the outer circumferential surface of the main transmission shaft 41. The outer circumferential surface of the ball engaging member 45c has rows of recesses 45d arranged circumferentially for accommodating balls 45a, and these rows are provided at two locations in the axial direction. Note that one row of recesses 45d and the other row of recesses 45d have recesses at different positions in the circumferential direction.

[0030] Furthermore, the main transmission member 45 has a first sleeve 68a having a main transmission shaft forward gear 68 and a second sleeve 69a having a main transmission shaft reverse gear 69, and the first sleeve 68a and the second sleeve 69a are provided so as to surround the main transmission shaft 41. The ball 45a corresponding to the main transmission shaft forward gear 68 is held in a through hole 68b formed in the first sleeve 68a, and the ball 45a corresponding to the main transmission shaft reverse gear 69 is held in a through hole 69b formed in the second sleeve 69a.

[0031] The shifter 45b is formed in an annular shape that surrounds the first sleeve 68a and the second sleeve 69a, and is configured to slide axially across the first sleeve 68a and the second sleeve 69a. An annular cavity 45e is formed on the inner circumferential surface of the shifter 45b at its axial center.

[0032] When the shifter 45b is shifted to the neutral shift position, as shown in Figure 8, the cavity 45e of the shifter 45b is positioned to straddle the through hole 68b of the first sleeve 68a and the through hole 69b of the second sleeve 69a, and each ball 45a is released into the cavity 45e. As a result, neither the first sleeve 68a nor the second sleeve 69a is fixed to the main transmission shaft 41, and neither the main transmission shaft forward gear 68 nor the main transmission shaft reverse gear 69 is fixed (connected) to the main transmission shaft 41, making power transmission from the main transmission shaft 41 impossible.

[0033] When the shifter 45b is shifted to the forward shift position on the second sleeve 69a side from the neutral shift position, the end of the shifter 45b on the first sleeve 68a side is positioned to correspond to the through hole 68b of the first sleeve 68a, and the ball 45a in the through hole 68b is pushed into the recess row 45d, thereby fixing the first sleeve 68a to the main transmission shaft 41, fixing (connecting) the main transmission shaft forward gear 68 to the main transmission shaft 41, and enabling power transmission from the main transmission shaft 41 to the sub-transmission shaft 42. In addition, the through hole 69b of the second sleeve 69a is positioned to correspond to the cavity 45e of the shifter 45b, and the ball 45a in the through hole 69b is released into the cavity 45e, so the second sleeve 69a is not fixed to the main transmission shaft 41, and therefore the main transmission shaft reverse gear 69 is not fixed (connected) to the main transmission shaft 41.

[0034] When the shifter 45b is shifted to the reverse shift position on the first sleeve 68a side from the neutral shift position, the end of the shifter 45b on the second sleeve 69a side is positioned to correspond to the through hole 69b of the second sleeve 69a, and the ball 45a in the through hole 69b is pushed into the recess row 45d, thereby fixing the second sleeve 69a to the main transmission shaft 41, fixing (connecting) the main transmission shaft reverse gear 69 to the main transmission shaft 41, and enabling power transmission from the main transmission shaft 41 to the sub-transmission shaft 42. Note that the through hole 68b of the first sleeve 68a is positioned to correspond to the cavity 45e of the shifter 45b, and the ball 45a in the through hole 68b is released into the cavity 45e, so the first sleeve 68a is not fixed to the main transmission shaft 41, and therefore the main transmission shaft forward gear 68 is not fixed (connected) to the main transmission shaft 41.

[0035] The auxiliary transmission member 47 has multiple gear shift positions, including a planting position and a moving position, and switches to any of these gear shift positions to change the speed of the power transmitted to the auxiliary transmission shaft 42. The auxiliary transmission member 47 may be composed of any gear shifting means, such as a slide gear, but in this embodiment, an example in which it is composed of a slide gear is shown.

[0036] The auxiliary transmission member 47 is composed of a slide gear having a relatively large-diameter planting gear 47a corresponding to the planting position and a relatively small-diameter moving gear 47b corresponding to the moving position. When the auxiliary transmission member 47 is switched to the planting position, the large-diameter planting gear 47a is connected (meets) with the main transmission shaft forward gear 68, transmitting power to the auxiliary transmission shaft 42 at a relatively low speed. When the auxiliary transmission member 47 is switched to the moving position, the small-diameter moving gear 47b is connected (meets) with the main transmission shaft forward gear 68, transmitting power to the auxiliary transmission shaft 42 at a relatively high speed. As shown in Figures 2 and 9, an auxiliary transmission drive member 53, such as an actuator that performs the switching drive, is attached to the auxiliary transmission member 47, and a stepped transmission operating unit 66, such as a drive motor that operates the auxiliary transmission drive member 53, is connected to the auxiliary transmission drive member 53. The stepped transmission operating unit 66 is controlled and operated by the control device 4, which activates the sub-transmission drive member 53 to drive the sub-transmission member 47 to switch.

[0037] The second transmission gear 49 of the auxiliary transmission shaft 42 is connected (meets) with the front wheel output gear 55 provided on the front wheel output shaft 54, and transmits the power transmitted to the auxiliary transmission shaft 42 to the front wheel output shaft 54 ​​via the front wheel output gear 55. In addition, the first transmission gear 48 of the auxiliary transmission shaft 42 is connected (meets) with the rear wheel output gear 60 provided on the rear wheel output shaft 59 via the third transmission gear 56, fourth transmission gear 57, fifth transmission gear 58, etc., and transmits the power transmitted to the auxiliary transmission shaft 42 to the rear wheel output shaft 59 via the rear wheel output gear 60.

[0038] The first PTO gear 46 of the main transmission shaft 41 is connected (meets) with the second PTO gear 50 of the auxiliary transmission shaft 42, and transmits the power transmitted to the main transmission shaft 41 to the auxiliary transmission shaft 42 via the second PTO gear 50. Furthermore, the second PTO gear 50 of the auxiliary transmission shaft 42 is connected (meets) with the PTO output gear 64 provided on the PTO output shaft 63 via the sixth transmission gear 61, the seventh transmission gear 62, etc., and transmits the power transmitted to the auxiliary transmission shaft 42 to the PTO output shaft 63 via the PTO output gear 64.

[0039] The brake 44 is attached to the auxiliary transmission shaft 42 and, when activated, brakes the rotation of the auxiliary transmission shaft 42 and restricts power transmission. As shown in Figures 2 and 9, the brake 44 is fitted with a brake drive member 65, such as an actuator, which switches between an activated (ON) state and an activated (OFF) state. A stepped transmission actuation unit 66, such as a drive motor, which operates the brake drive member 65, is connected to the brake drive member 65. The stepped transmission actuation unit 66 is controlled and operated by the control device 4 to operate the brake drive member 65 and switch the auxiliary transmission member 47. Furthermore, the brake drive member 65 switches between the activated and deactivated states of the brake 44 in response to the operation of a brake operating member 67, such as a brake pedal, or in response to the drive to switch the stepped transmission 40 to the neutral position, as controlled by the control device 4.

[0040] Next, the control unit 4 will be described. As shown in Figure 9, the control unit 4 is composed of a computer such as a CPU and is connected to storage units 5 such as ROM, RAM, hard disk drive, and flash memory.

[0041] The memory unit 5 stores programs and data for controlling various components and functions of the rice transplanter 1, and the control device 4 controls the various components and functions by performing calculations based on the programs and data stored in the memory unit 5.

[0042] The control device 4 operates as a gear shift control unit 70 (control unit) by executing a program stored in the memory unit 5. The gear shift control unit 70 controls gear shifting by the continuously variable transmission 30 and gear shifting by the stepped transmission 40. The gear shift control unit 70 implements the gear shift control process of the gear shift control method according to the present invention.

[0043] The gear shift control unit 70, in order to control the gear shift of the continuously variable transmission 30, basically detects the operating state of the adjustment operation of the continuously variable transmission 30 by the gear shift pedal 17 using the continuously variable operation detection unit 17a, and based on the detection result, operates the continuously variable transmission operating unit 34 to adjust and drive the continuously variable transmission drive member 33 to control the continuously variable transmission 30. In this way, the gear shift control unit 70 continuously adjusts the power transmitted from the engine 11 to the running parts of the pair of front wheels 13 and the pair of rear wheels 14. For example, the gear shift control unit 70 detects the opening degree of the gear shift pedal 17 using the continuously variable operation detection unit 17a and controls the power of the continuously variable transmission 30 to change according to the opening degree of the gear shift pedal 17.

[0044] The gear shift control unit 70, in order to control the gear shift of the stepped transmission 40, basically detects the operation status of the gear shift operation of the stepped transmission 40 by the gear shift lever 18 using the stepped operation detection unit 18a, and based on the detection result, operates the stepped transmission operation unit 66 to switch and drive the main gear shift drive member 52 and the sub-gear shift drive member 53 to control the stepped transmission 40. As a result, the gear shift control unit 70 shifts the power transmitted from the engine 11 to the running gears of the pair of front wheels 13 and the pair of rear wheels 14 to one of the multiple gear positions.

[0045] For example, when the gear lever 18 is switched to forward operation 18b, neutral operation 18c, or reverse operation 18d, the gear control unit 70 controls the main gear drive member 45 to switch to the corresponding forward position, neutral position, or reverse position via the main gear drive member 52 to change the power of the stepped transmission 40. Also, when the gear lever 18 is switched to planting operation 18e or moving operation 18f, the gear control unit 70 controls the sub-gear drive member 53 to switch the sub-gear drive member 47 to the corresponding planting position or moving position to change the power of the stepped transmission 40. Furthermore, when the gear lever 18 is switched to seedling transplanting operation 18g, the gear control unit 70 controls the main gear drive member 52 to switch the main gear drive member 45 to the neutral position.

[0046] In this embodiment, in particular, when the gear shift control unit 18a detects that a gear shift operation of the gear shift device 40 has been performed by the gear shift lever 18, the gear shift control unit 70 controls the main gear shift shaft 41 (gear shift shaft) to rotate in a predetermined rotational direction. Then, provided that the gear shift position change drive of the gear shift device 40 corresponding to the gear shift operation by the gear shift lever 18 has not been completed, the gear shift control unit 70 controls the continuously variable transmission 30 to rotate the main gear shift shaft 41 (gear shift shaft), which is rotating in the predetermined rotational direction, in the opposite direction to the predetermined rotational direction. The continuously variable transmission 30 is configured to rotate the main gear shift shaft 41 in a predetermined rotational direction regardless of the gear shift position of the gear shift device 40. For example, even in the neutral position, the main gear shift shaft 41 is subjected to creep rotation (slight rotation).

[0047] At this time, the gear shift control unit 70 may add the condition that the rice transplanter 1 is stopped (travel speed is 0) to the conditions for rotating the main gear shift shaft 41 in reverse. For example, when the gear shift control unit 70 detects that a switching operation has been performed by the gear shift lever 18 using the stepped operation detection unit 18a, it activates the stepped gear shift operating unit 66 to drive the brake drive member 65 and activate the brake 44, thereby stopping the rice transplanter 1 from travel.

[0048] Furthermore, the gear shift control unit 70 controls the brake 44 to activate, and then, when the stepped transmission 40 has completed a gear shift and a predetermined operation of the gear shift pedal 17 has been performed, it controls the brake drive member 65 to release the brake 44 and return it to a non-activated state. For example, the gear shift control unit 70 detects the operation state of the gear shift pedal 17 with the stepless operation detection unit 17a, and defines the operation in which the gear shift pedal 17 is returned to a predetermined value or less (an operation in which the opening degree of the gear shift pedal 17 becomes 30% or less of the fully open position) as a predetermined operation.

[0049] The gear shift control unit 70 may control the main gear shift shaft 41 to rotate in the reverse direction after rotating it for a predetermined time. The gear shift control unit 70 may set the time for rotating the main gear shift shaft 41 according to the target gear shift position of the stepped gear shift drive 40. In addition, when the gear shift control unit 70 detects a gear shift operation by the gear shift lever 18 using the stepped operation detection unit 18a, it may increase the rotational speed at which the main gear shift shaft 41 rotates in the predetermined direction by controlling the continuously variable transmission 30 before rotating the main gear shift shaft 41 in the reverse direction. Alternatively, if the main gear shift shaft 41 is creeping, the gear shift control unit 70 may control it to increase the creep rotation speed.

[0050] For example, if the gear shift control unit 70 detects a gear shift operation by the gear shift lever 18 using the stepped operation detection unit 18a and a predetermined switching time has elapsed, the gear shift control unit 70 determines that the gear shift drive of the stepped gear shift device 40 is not complete and controls the continuously variable transmission 30 to rotate the main gear shift shaft 41 in the reverse direction.

[0051] The gear shift control unit 70 may set the switching time for initiating the reverse rotation of the main gear shift shaft 41 according to the target gear shift position of the gear shift drive of the stepped gear shift device 40. For example, the gear shift control unit 70 sets the switching time for the gear shift drive when the target gear shift position is the neutral position to be shorter than the switching time for the gear shift drive when the target gear shift position is the forward position or the reverse position.

[0052] Furthermore, the gear shift control unit 70 sets the number of rotations that reverses the main gear shift shaft 41 to a very small number of rotations by controlling the continuously variable transmission 30, and it is preferable to set this according to the target gear shift position of the stepped transmission 40's switching drive. For example, the gear shift control unit 70 sets the number of rotations that reverses the main gear shift shaft 41 when the target gear shift position is the forward or reverse position to be less than the number of rotations that reverses the main gear shift shaft 41 when the target gear shift position is the neutral position.

[0053] Furthermore, when the gear shift control unit 70 detects a switching operation by the gear shift lever 18 using the stepped operation detection unit 18a, it may control the continuously variable transmission 30 by alternately repeating the rotation of the main gear shift shaft 41 in a predetermined direction and the rotation in the opposite direction until it determines that the switching drive of the stepped gear shift device 40 is complete.

[0054] Furthermore, in response to the shifting operation by the shift lever 18, when the drive to switch the shift position of the stepped transmission 40 is completed, the shift control unit 70 may notify the operator of the completion of the shift by displaying it on a display (not shown) or by outputting sound through a speaker (not shown).

[0055] Next, an example of the operation of changing the speed of the stepped transmission 40 in the rice transplanter 1 will be explained with reference to the flowchart in Figure 10.

[0056] First, while the rice transplanter 1 is stopped and its gear shift lever 18 is in the neutral position 18c (Step S1), the operator switches the gear shift lever 18 from the neutral position 18c to the forward position 18b (Step S2).

[0057] In response to the switching operation of the gear lever 18, the gear control unit 70 starts the switching drive of the stepped gear transmission 40, controls the stepped gear operation unit 66 to start the switching drive of the main gear drive member 52, and controls the main gear drive member 45 to shift from the neutral position, which is the current gear position, to the forward position (step S3). At this time, in response to the switching operation of the gear lever 18, the gear control unit 70 controls the stepped gear operation unit 66 to drive the brake drive member 65 to activate the brake 44 and bring the rice transplanter 1 to a stop (step S4).

[0058] Subsequently, the gear shift control unit 70 determines whether the gear shift drive of the gear shift device 40 has been completed within a predetermined switching time elapsed since the gear shift lever 18 was detected by the gear shift operation detection unit 18a (step S5). If the gear shift drive of the gear shift device 40 has been completed within the switching time elapsed (step S5: Yes), the gear shift control unit 70 controls the gear shift operation unit 66 to drive the brake drive member 65 and release the brake 44 (step S6).

[0059] On the other hand, if the switching drive of the stepped transmission 40 is not completed before the switching time has elapsed (Step S5: No), the transmission control unit 70 controls the continuously variable transmission 30 to rotate the main transmission shaft 41 of the stepped transmission 40, which is rotating in a predetermined rotation direction, in the opposite direction to the predetermined rotation direction (Step S7). Also, when a predetermined reversal time has elapsed since the main transmission shaft 41 started to rotate in the reverse direction (Step S8: Yes), the transmission control unit 70 controls the main transmission shaft 41 to rotate back in the predetermined rotation direction (Step S9). Then, when the switching drive of the stepped transmission 40 is completed (Step S10), the transmission control unit 70 controls the stepped transmission operating unit 66 to drive the brake driving member 65 and release the brake 44 (Step S6).

[0060] As described above, according to this embodiment, the rice transplanter 1, which is an example of a work vehicle, comprises a stepped transmission 40, a gear lever 18 which is a stepped transmission operation unit, and a control device 4 which functions as a gear control unit 70 (control unit). The stepped transmission 40 switches to one of a plurality of gear positions to change the power transmitted from the engine 11 (power source) to the running parts of a pair of front wheels 13 and a pair of rear wheels 14. The gear lever 18 receives the switching operation of the stepped transmission 40. The gear control unit 70 controls the switching drive of the stepped transmission 40 based on the detection result of the switching operation by the gear lever 18. The stepped transmission 40 has a main gear member 45 (gear member) which can be switched to one of a plurality of gear positions, and a main gear shaft 41 (gear shaft) which pivotally supports the main gear member 45. If the gear shift control unit 70 determines that the stepped gear shift device 40 has not completed the drive to switch to the gear position corresponding to the shifting operation by the gear shift lever 18, it controls the main gear shift shaft 41 to rotate in a predetermined direction. Furthermore, if the gear shift control unit 70 determines that the stepped gear shift device 40 has not completed the drive to switch gears even after a predetermined time has elapsed since the main gear shift shaft 41 was rotated in the predetermined direction, it controls the main gear shift shaft 41 to rotate in the opposite direction to the predetermined direction.

[0061] As a result, even if problems such as a phase misalignment of the clutch, which is the main transmission component 45, or torque stagnation due to gear engagement occur during the shifting drive of the stepped transmission 40 of the rice transplanter 1, the main transmission shaft 41 can be rotated in reverse to smoothly complete the shifting drive.

[0062] Furthermore, according to this embodiment, in the rice transplanter 1, the speed control unit 70 sets the number of rotations that rotate the main speed shaft 41 in the reverse direction according to the target speed position of the stepped speed transmission 40.

[0063] As a result, in the rice transplanter 1, due to the structure of the clutch, which is the main transmission member 45, the rotational speed of the main transmission shaft 41 suitable for shifting gears differs depending on whether the gear is shifting from the forward or reverse position to the neutral position or from the neutral position to the forward or reverse position. This makes it possible to perform shifting gears appropriately according to the gear position. For example, when shifting the main transmission member 45 to the neutral position, the rotational speed of the main transmission shaft 41 can be reduced compared to when shifting to the forward or reverse position. Therefore, the time required to complete the shifting drive of the stepped transmission 40 can be shortened.

[0064] Furthermore, according to this embodiment, in the rice transplanter 1, the gear shift control unit 70 sets the switching time from the time it detects the switching operation by the gear shift lever 18 until it rotates the main gear shift shaft 41 in the reverse direction, according to the target gear shift position of the stepped gear shift device 40.

[0065] As a result, in the rice transplanter 1, the structure of the clutch, which is the main transmission member 45, can cause problems such as torque lock-up depending on the gear position. However, by setting the switching time for initiating reverse rotation of the main transmission shaft 41 to a time appropriate for each target gear position, the switching drive can be completed more smoothly. For example, when shifting the main transmission member 45 to the neutral position, torque lock-up can increase the required driving force, which may prevent smooth gear shifting. Therefore, by setting a shorter switching time compared to shifting to the forward or reverse position and initiating reverse rotation at an earlier timing, the switching drive can be completed more smoothly.

[0066] Furthermore, according to this embodiment, the rice transplanter 1 is equipped with a continuously variable transmission 30 that adjusts the power transmitted to the travel unit, the main transmission shaft 41 is configured to transmit power from the continuously variable transmission 30 to a stepped transmission 40, and the transmission control unit 70 controls the continuously variable transmission 30 to rotate the main transmission shaft 41 in the opposite direction to a predetermined rotation direction.

[0067] In the above-described embodiment, the stepped transmission 40 of the rice transplanter 1 was shown to have multiple gear positions, namely a forward position, a neutral position, and a reverse position. However, the present invention is not limited to this example. As another example, the stepped transmission 40 may be configured to have multiple gear positions, namely a low-speed position, a medium-speed position, a high-speed position, and so on.

[0068] Furthermore, in the above-described embodiment, the stepped transmission 40 of the rice transplanter 1 is equipped with a stepped transmission operating unit 66 that operates the main transmission drive member 52, and when a switching operation by the transmission lever 18 is detected by the stepped operation detection unit 18a, the transmission control unit 70 operates the stepped transmission operating unit 66 to switch the main transmission drive member 52 and the auxiliary transmission drive member 53. However, the present invention is not limited to this example. As another example, the stepped transmission 40 may be equipped with a connecting member that connects the transmission lever 18 to the main transmission drive member 52 and the auxiliary transmission drive member 53, and the switching operation by the transmission lever 18 may be transmitted to the main transmission drive member 52 and the auxiliary transmission drive member 53 via the connecting member. Even in this case, if the gear shift control unit 70 detects a switching operation by the gear shift lever 18 using the stepped operation detection unit 18a, and the gear shift position switching drive of the stepped transmission 40 corresponding to the switching operation by the gear shift lever 18 has not been completed, the gear shift control unit 70 controls the continuously variable transmission 30 to rotate the main gear shift shaft 41, which is rotating in a predetermined rotational direction, in the opposite direction.

[0069] In the embodiments described above, an example was explained in which the work vehicle of the present invention is composed of a rice transplanter 1. However, the present invention is not limited to this example, and the work vehicle of the present invention may be composed of other agricultural machinery such as tractors, combine harvesters, and lawnmowers, or other work vehicles other than agricultural machinery.

[0070] Furthermore, the present invention may be modified as appropriate, provided that it does not contradict the gist or idea of ​​the invention as can be inferred from the claims and the specification as a whole, and work vehicles with such modifications are also included in the technical concept of the present invention.

[0071] [Notes on the invention] The following is an overview of the invention extracted from the above-described embodiments. Note that each configuration and processing function described below can be selected and combined as desired.

[0072] <Note 1> A stepped transmission that switches between multiple gear positions to change the speed of power transmitted from the power source to the drive unit, A stepped gear shift operation unit that receives the switching operation of the stepped gear shift device, The system includes a control unit that controls the switching drive of the stepped transmission based on the detection result of the switching operation by the stepped transmission operation unit, The aforementioned stepped transmission device comprises a gear shifting member that can be switched to any of the plurality of gear shifting positions, and a gear shifting shaft that pivotally supports the gear shifting member. A work vehicle characterized in that, when the control unit determines that the stepped transmission has not completed the drive to switch to the gear position corresponding to the switching operation by the stepped transmission operation unit, it controls the gear shaft to rotate in the predetermined rotation direction.

[0073] <Note 2> The work vehicle according to Appendix 1, characterized in that if the control unit determines that the stepped transmission has not completed the switching drive even after a predetermined time has elapsed since the transmission shaft was rotated in the predetermined rotation direction, it controls the transmission shaft to rotate in the opposite direction to the predetermined rotation direction.

[0074] <Note 3> The work vehicle according to Appendix 2, characterized in that the control unit sets the rotational speed for rotating the gear shift shaft in the reverse direction according to the target gear shift position of the stepped transmission.

[0075] <Note 4> The work vehicle according to any one of the appendices 1 to 3, characterized in that the control unit sets the switching time from the detection of the switching operation by the stepped gear shift operation unit until the gear shift shaft is rotated in the reverse direction, according to the target gear shift position of the stepped gear shift device.

[0076] <Note 5> The system further includes a continuously variable transmission that adjusts the power transmitted to the aforementioned running section. The aforementioned transmission shaft is configured to transmit power from the continuously variable transmission to the stepped transmission, The work vehicle according to any one of the appendices 2 to 4, characterized in that the control unit controls the continuously variable transmission to rotate the transmission shaft in the opposite direction to the predetermined rotation direction. [Explanation of Symbols]

[0077] 1. Rice transplanter (work vehicle) 2. Body 3 Planting area 4. Control device 11. Engine (power source) 12 Transmission 13 Front wheels (running section) 14. Rear wheels (running section) 18. Gear shift lever (stepped gear shift operation part) 18a Stepped operation detection section 30 Continuously Variable Transmission 33 Continuously Variable Speed ​​Drive Member 34 Continuously Variable Speed ​​Operating Unit 40-speed transmission 41 Main transmission shaft (transmission shaft) 45 Main transmission component (transmission component) 47 Sub-transmission component 52 Main transmission drive member 53 Sub-transmission drive member 66 Stepped transmission operating mechanism 70. Gear shift control unit (control unit)

Claims

1. A stepped transmission that switches between multiple gear positions to change the speed of power transmitted from the power source to the drive unit, A stepped gear shift operation unit that receives the switching operation of the stepped gear shift device, The system includes a control unit that controls the switching drive of the stepped transmission based on the detection result of the switching operation by the stepped transmission operation unit, The aforementioned stepped transmission device comprises a gear shifting member that can be switched to any of the plurality of gear shifting positions, and a gear shifting shaft that pivotally supports the gear shifting member. If the control unit determines that the stepped transmission has not completed the drive to switch to the gear position corresponding to the switching operation by the stepped transmission operation unit, it controls the gear shaft to rotate in a predetermined rotational direction. The control unit is characterized in that, if it determines that the stepped transmission has not completed the switching drive even after a predetermined time has elapsed since the transmission shaft was rotated in the predetermined rotation direction, it controls the transmission shaft to rotate in the opposite direction to the predetermined rotation direction.

2. The work vehicle according to claim 1, characterized in that the control unit sets the rotational speed for rotating the gear shift shaft in the reverse direction according to the target gear shift position of the stepped transmission.

3. The work vehicle according to claim 1, characterized in that the control unit sets the switching time from the detection of the switching operation by the stepped gear shift operation unit to the rotation of the gear shift shaft in the reverse direction according to the target gear shift position of the stepped gear shift device.

4. The system further includes a continuously variable transmission that adjusts the power transmitted to the aforementioned running section. The aforementioned transmission shaft is configured to transmit power from the continuously variable transmission to the stepped transmission, The work vehicle according to claim 1, characterized in that the control unit controls the continuously variable transmission to rotate the transmission shaft in the opposite direction to the predetermined rotation direction.

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